The present invention generally relates to apparatus for flowing fluids into enclosed spaces and, in a preferred embodiment thereof, more particularly relates to apparatus for flowing refrigerant fluid, such as a treatment oil, into an air conditioning system.
An embodiment of the invention illustrated and described in U.S. Pat. No. 5,070,917 to Ferris et al utilizes a source of pressurized refrigerant fluid to force a quantity of refrigerant treatment liquid, representatively a leak-inhibiting liquid, into an air conditioning refrigerant circuit from a tubular container in which the treatment liquid is sealingly stored. This apparatus was designed for use with refrigerant circuits which utilized R-12 refrigerant and had screw-threaded inlet and outlet connection fittings connected to hollow inlet and outlet members extending into opposite ends of the hollow, liquid-containing body portion of the apparatus.
Each of the inlet and outlet members had associated therewith a check valve structure serving to prevent undesirable treatment liquid backflow through the apparatus body portion from its outlet to its outlet. The check valve structure at each of the inlet and outlet members comprised an annular sidewall groove formed in the member, a pair of openings extending laterally through the groove into the hollow interior of the member, and an elastomeric O-ring member received in the annular groove and normally covering the lateral openings therein.
In a subsequently marketed version of this refrigerant liquid injection apparatus, the inlet member was reconfigured and modified in a manner permitting it to be threadingly advanced through the interior of the apparatus body in a manner permitting the user to mechanically force the treatment fluid out of the body as an alternative to using pressurized fluid flowed through the inlet member to force the treatment liquid outwardly from the body into the refrigerant circuit.
More recently manufactured refrigerant circuits are filled with R-134a refrigerant (which has replaced the previously utilized R-12 refrigerant) and have standardized R-134a service fittings with non-externally threaded configurations. Due to these changes in the service fitting configuration and the type of refrigerant used in modern R-134a air conditioning refrigerant circuits, the refrigerant treatment liquid injection apparatus shown in the aforementioned U.S. Pat. No. 5,070,917 (or as later modified as described above) cannot be conveniently utilized in conjunction with an R134a refrigerant circuit. Additionally, the previously described check valve structures have proven to provide certain manufacturing difficulties.
From the foregoing it can be seen that it would be desirable to provide a refrigerant fluid injection apparatus, of the general type described above, in which the apparatus was suitable for use with an R-134a refrigerant system and was provided with improved check valve structures. It is to these goals that the present invention is directed.